Coupling of multicomponent thermodynamic databases to a phase-field model:: Application to γ′ growth in a ternary Ni-Al-Cr model superalloy

The paper presents a multicomponent multi-phase-field model which has been coupled to the software Thermo-Gale to obtain molar Gibbs energies and chemical potentials from thermodynamic databases. These databases, which have been assessed according to the CALPHAD approach, provide realistic thermodynamic descriptions for all phases present in a given material. Furthermore, the diffusion matrix of the multicomponent Fick-Onsager diffusion equations is calculated by a subroutine of Dictra. This model is applied to the growth of the gamma' phase in a ternary Ni-Al-Cr alloy. The first numerical example is a benchmark test, which compares a 1D solution with a sharp interface calculation performed by Dictra. The second example is a 2D simulation of Ostwald-ripening in an Ni-Al-Cr alloy which was intended to quantitatively simulate an experiment on coarsening of the gamma' phase. The results principally show the feasibility of quantitatively simulating diffusion controlled phase transformations in technical alloys.